Number of planets in solar system in doubt

Scientists have indicated that by the end of 2006 we could have one extra planet in the solar system, or one fewer.

The problem arose after German scientists measured the size of the so-called tenth planet, nicknamed Xena or UB313. The object is approximately 3,000km in diameter, making it 700km larger than Pluto but smaller than Earth's moon. 

Professor Frank Bertoldi published his research in Nature but the discovery has sparked intense debate over whether to include the object, making it the tenth planet in the solar system, or to exclude Pluto from being counted as part of the solar system.

The International Astronomical Union is currently formulating the standards as to what constitutes a planet and should publish its findings by the end of the year.

Xena also has a moon, like Pluto, nicknamed Gabrielle after Xena's sidekick in the TV series. 

If object is deemed a planet it will be renamed after a god from Greco-Roman mythology, most likely Persephone who was Pluto's consort.

Arthur C Clarke and Douglas Adams named the tenth planet Persephone in their books, although Adams suggested that the planet's nickname was 'Rupert'.